Thursday, January 28, 2010

Chill Out

Where are the coldest places in the universe?

The coldest temperature measured on Earth’s surface was at Vostok, Antarctica. In 1983, it reached minus 129 degrees Fahrenheit there.

The coldest place in our solar system is Neptune’s moon Triton, at minus 315 degrees Fahrenheit.

Two of the coldest known places in the universe are:
- intergalactic space, at an inhospitable minus 455 degrees Fahrenheit, and
- the Boomerang Nebula, a gas cloud being expelled by a dying star in our Milky Way Galaxy. At minus 457.6 degrees Fahrenheit, it’s currently the coldest known spot in the universe.


What’s the Ultimate Cold?

Absolute zero, the coldest theoretical temperature, is minus 459.67 degrees Fahrenheit. It has not yet been measured at any location, although scientists creating controlled environments in laboratories on Earth have come within a fraction of one degree.

Thursday, January 21, 2010

That's Hot

Where are the hottest places in the universe?

The hottest temperature measured on Earth’s surface was in the Lut Desert in Iran. In 2005, it reached 159 degrees Fahrenheit there.

The hottest place in our solar system is the center of our Sun, a sizzling 27 million degrees Fahrenheit.

Two of the hottest known places in the universe are:
- the cores of exploding stars called supernovas, at 100 billion degrees Fahrenheit, and
- inside gamma ray bursts— mysterious, energetic explosions originating from distant galaxies— estimated at a blistering 1 trillion degrees Fahrenheit.


What’s the Ultimate Hot?

The Big Bang, with an estimated temperature of 1-followed-by-32-zeros Kelvin, equivalent to 1.8-followed-by-32-zeros Fahrenheit.

Now that’s hot!

Thursday, January 14, 2010

Where Does Space Begin?

Space. We all know it’s the “final frontier.” But when you look up at the night sky from Planet Earth, where exactly does outer space begin?

To answer this question, we can first consider the dictionary definition of space: the region beyond Earth’s atmosphere. When you look up, you’re looking through many miles of the protective envelope of gases we call atmosphere. Earth’s atmosphere is composed primarily of elemental gases: more than 75% nitrogen, less than 25% oxygen, and about 1% argon. The remainder is an assortment of trace gases, as well as molecules such as carbon dioxide, ozone, and water.

Earth’s atmosphere is typically divided into five layers, and the demarcation of the layers is based upon whether temperature increases or decreases with altitude within the layer. The altitude ranges shown for the layers are approximate; they’re not precise or fixed measurements, because these altitudes can vary somewhat according to the season and the latitude of your location on Earth.

Looking up, your gaze crosses these layers, from lowest to highest:

#1 Troposphere - first 10 miles above sea level. Nearly all weather and clouds are found here, and most commercial aircraft fly in the upper troposphere. Although we stargazers normally revile clouds, this is a case where spotting one can orient you on your journey to outer space. Or simply look for the lights of a high-flying jet.

#2 Stratosphere - 10 to 30 miles. The stratosphere contains the important ozone layer, a protective band of specialized oxygen molecules that absorbs UV radiation from the Sun. The stratosphere is the upper limit of high-altitude weather balloons.

#3 Mesosphere - 30 to 50 miles. This is the layer where most meteors burn up, so look for a “shooting star” to locate the mesosphere. Strange clouds called noctilucent clouds,
and oddball types of lightning such as sprites and elves are also spotted in this layer.

#4 Thermosphere - 50 to 400 miles. The International Space Station (ISS) and the Hubble Space Telescope orbit high in the thermosphere. Consult this website to find out when you can watch the ISS pass overhead in your area; it’s very easy to spot since it’s so bright.

If you’re so lucky as to live far enough north to see the colorful spectacle of an aurora, aka the Northern Lights, you’re seeing solar particles colliding with atmospheric gases in the thermosphere.

#5 Exosphere - 400 to 800 miles. This layer is where stray atoms and molecules from Earth’s outer atmosphere escape into space. Hydrogen and helium, the two most common elements in the universe, are the main ingredients of the exosphere.

So, where does space begin? Unfortunately, there is no well-placed “Welcome to Outer Space” sign up there. The Earth’s atmosphere simply gets thinner and thinner (that is, less dense) with increasing altitude until it gradually merges with the cold expanse of space. However, since around the middle of the Twentieth Century, space has commonly been considered to begin at 62 miles (100 km) above sea level, just slightly into the thermosphere layer. This is where the atmosphere becomes too thin for aircraft to maintain altitude, in other words, where astronauts must replace aeronauts.

Can you see it? Somewhere between shooting stars and the Space Station, the final frontier begins.

Thursday, January 7, 2010

Index of Posts 2007-2009

Search this alphabetical index to find posts about specific constellations, planets, and other topics, indexed by the month and year they appeared. This index covers posts from 2007 through 2009. The majority of posts focus on stars (and other celestial objects) that you can see with the naked eye.



POST LOCATOR BY TOPIC

Andromeda Oct 2008
Andromeda Galaxy Dec 2009
Aquarius Oct 2009
Aries Nov 2008
Auriga Jan 2009
Bootes Oct 2008, Jun 2009
Burro Nebula Sep 2009
Camelopardalis Feb 2009
Cancer Apr 2008
Canis Major Feb 2008
Canis Minor Feb 2008
Capricornus Sep 2009, Oct 2009
Cassiopeia Dec 2007, Sep 2009
Cepheus Jan 2008
Cetus Dec 2009
Coma Berenices May 2009
Comets Nov 2007
Corona Australis Aug 2008
Corona Borealis Aug 2008
Corvus Jun 2009
Delphinus Oct 2008
Draco Jun 2009
Equilux Mar 2008
Equinox Mar 2008
Equuleus Oct 2009
Eridanus Jan 2009
Galileo Jan 2008, Jan 2009
Gemini Dec 2007, Feb 2009
Hercules Sep 2008
Jupiter Jul 2008
Lacerta Dec 2008
Lepus Feb 2008
Libra Jul 2009
Mercury May 2008
Meteors Dec 2007, Aug 2008, Apr 2009
Milky Way Dec 2008
Moon Nov 2007, Mar 2008, Apr 2008, May 2008, Jun 2008, Jul 2008, Sep 2008, Nov 2008, Dec 2008, Jul, 2009, Nov 2009, Dec 2009
Movies May 2008
Music Aug 2008
Ophiuchus July 2009, Aug 2009
Orion Jan 2008, Feb 2008
Pegasus Dec 2007
Perseus Mar 2009
Pisces Nov 2009
Piscis Australis Nov 2009
Puppis Feb 2009
Sagittarius Aug 2009
Satellites Oct 2008
Saturn Dec 2008, Apr 2009
Scorpius Jul 2008
Serpens Jul 2009
Solstice Dec 2007
Summer Triangle Oct 2008
Taurus Jan 2008
Telescopes Nov 2007, Jan 2008
Triangulum Jan 2009
Ursa Major Jun 2008, May 2009
Ursa Minor Jun 2008
Venus Jan 2008, Feb 2009, Mar 2009
Virgo Apr 2009
Websites Mar 2009
Whirlpool Galaxy May 2008
Winter Hexagon Mar 2008
Zodiacal Light Mar 2008